Why does overflow clear float have no effect?

The reason why overflow clearing float is invalid may be that the height of the floating element is not set, the floating element is cleared, the clearing element is before the floating element, the height of the clear element is not set, or the clear element is after the floating element, etc. Detailed introduction: 1. The height of the floating element is not set. When the height of the floating element is not set, it may not be cleared. The height of the floating element is determined by its content, so if the content has no height, the floating element also has no height; 2. Floating The element is cleared, when the floated element is cleared, the overflow property may not clear and so on.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

In CSS, the overflow attribute is used to control the content overflow of an element. However, when an element contains floated elements, the overflow property may not clear the floats. Here are some reasons:

1. The height of the floating element is not set:

When the height of the floating element is not set, it may not be cleared. The height of a floated element is determined by its content, so if the content has no height, then the floated element has no height either.

   .parent {
     overflow: hidden;
   }
   .child {
     float: left;
   }

In the above example, the overflow attribute of the .parent element cannot clear the float of the .child element.

2. Floating elements are cleared:

When floating elements are cleared, the overflow attribute may not be cleared. If a floated element is cleared, it will not affect other elements.

   .parent {
     overflow: hidden;
   }
   .child {
     float: left;
     clear: both;
   }

In the above example, the .child element is cleared, and the overflow attribute of the .parent element cannot clear the float.

3. Floating elements before clearing elements:

When floating elements are before clearing elements, the overflow attribute may not be cleared. If the floated element precedes the cleared element, the cleared element cannot clear the float.

   .parent {
     overflow: hidden;
   }
   .child {
     float: left;
   }
   .clear {
     clear: both;
   }

In the above example, the .clear element is after the floating element, and the overflow attribute of the .parent element cannot clear the floating element.

4. The height of the cleared element is not set:

When the height of the cleared element is not set, the overflow attribute may not be able to clear the float. If the clear element has no height, then it won't affect other elements.

   .parent {
     overflow: hidden;
   }
   .child {
     float: left;
   }
   .clear {
     clear: both;
   }

In the above example, the .clear element does not have a height set, and the overflow attribute of the .parent element cannot clear the float.

5. Clear elements after floated elements:

When clear elements are after floated elements, the overflow property may not clear the float. If the clearing element comes after the floating element, the floating element cannot be cleared.

   .parent {
     overflow: hidden;
   }
   .child {
     float: left;
   }
   .clear {
     clear: both;
   }

In the above example, the .clear element is after the floating element, and the overflow attribute of the .parent element cannot clear the floating element.

These reasons may cause the overflow attribute to fail to clear the float. Depending on specific needs, the structure and style of the element can be adjusted to achieve effective clear floats.

It should be noted that clearing floats may cause layout problems for elements. When using clear floats, you should pay attention to the structure and style of elements to avoid overlapping or misalignment of elements.

In summary, the overflow attribute may not clear the float because the height of the floated element is not set, the floated element is cleared, the cleared element is before the floated element, the height of the cleared element is not set, or the cleared element is after the floated element. Proper use of clear floats can avoid element layout problems. If you have any further questions please feel free to let me know.

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